The present invention relates to a container for fixing an animal to be tested in a biochemical test of pharmacological or biochemical field. Such a container is used when enzymes existing in cells of a brain of the animal are deactivated in a moment with a microwave for the purpose of researching a distribution of the enzymes.
Hitherto, there are known two methods for heating with a microwave, one of which is a method where a microwave is applied to an object to be heated within an oven such as an electronic oven, and the other is a method where an object to be heated is put in a microwave transmission line such as a waveguide in which a microwave is transmitted. The latter method is effective to heat the object in a moment. However, the more a ratio of a sectional area of the object to be heated to a sectional area of the waveguide is increased, the larger becomes the temperature difference in the interior of the object, since the object to be heated is affected by a distribution of an electric field.
FIG. 1 is a sectional view showing a conventional microwave-heating-apparatus which employs the microwave transmission line. In FIG. 1, a waveguide, which is operated in TE.sub.10 mode and which generates an electric field in the direction of Arrow E, is used as a transmission line. An applicator 1 is formed by short-circuiting a finished end of the waveguide having a terminating plate 11 to short-circuit. An opening 13 is provided on a wall 12 of the applicator 1. The position of the opening is apart from the short-circuiting plate 11 by a predetermined distance. A head 21 of an animal 2 such as mouse or rat is inserted into the applicator 1 through the opening 13.
That is to say, the animal 2 is pushed into the container 3 by a pushing member 4 in a state that the head 21 is directed forward. The motion of the animal 2 is stopped by fixing the pushing member 4. The pushing member 4 is fixed by engaging an engaging plate 5 with a cutting portion 303 of the container 3. Numeral 41 indicates a shaft of the pushing member 4. Numeral 42 indicates grooves provided on the pushing member 4. The goove 42 is engaged with the engaging plate 5.
A tubular chamber 6 is secured to the applicator 1 so that an end of the tubular chamber 6 surrounds the opening 13 of the applicator 1 and the tubular chamber 6 extends from the opening 13 outwardly in an axial direction of the opening 13. The container 3 has a body portion 301 for covering a body of the animal, and a tubular portion 302 for covering a head 21 of the animal 2. The container 3 is inserted into the tubular chamber 6. In that case, the tubular portion 302 of the container 3 projects into the interior of the applicator 1 through the opening 13. The tubular portion 302 is made of a material having a high transparency, a low dielectric constant and a low dielectric loss such as a plastic.
However, in such a microwave-heating-apparatus, when the microwave of TE.sub.10 mode travels within the applicator 1 in the direction of Arrow A, an electric field E within the applicator 1 has a maximum value at a point on a central axial line a of the waveguide and an electric power (.alpha.E.sup.2) within the applicator 1 has an excessive maximum value at the point on the central axial line a of the waveguide (shown in FIG. 2A).
Accordingly, when the head 21 to be heated of the animal 2 is very small in volume and size in comparison with a wavelength-in-waveguide .lambda..sub.g of the used microwave, the temperature difference in the interior of the head 21 is so small that the difference can be ignored. However, in proportion to the increase in volume and size of the head 21 to be heated, the temperature difference in the interior of the head 21 becomes so large that the difference cannot be ignored, due to the excessive affection of a distribution of an electric field.
Particularly, when the microwave is applied to the head 21 until both sides of the head 21 are sufficiently heated, a part of the head 2a on the central axial line a is excessively heated. As a result, an important and fine brain tissue, such as a hypothalamus, existing on the central axial line a is easily destroyed.
When the head 21 of the tested animal 2 rotates a little in the direction of Arrow B shown in FIG. 2B under heating, the temperature difference between a right side and a left side of the head 21 is increased. That is to say, one side of the brain 22 is excessively heated and the other side of the brain 22 is insufficiently heated. In that case, it is impossible to uniformly heat the brain 22. As a result, a distribution of enzymes in the brain cannot be disadvantageously researched.